Bloodhound SSC: How do you build a car capable of 1,000mph?

Rockets and jets power a land speed record attempt and STEM outreach project.

Human beings achieved many 'firsts' in the 20th century. We climbed the planet's highest mountains, dived its deepest undersea trench, flew over it faster than the speed of sound, and even escaped it altogether in order to visit the moon. Beyond visiting Mars, it may feel like there are no more milestones left to reach. Yet people are still trying to push the envelope, even if they have to travel a little farther to get there.

Richard Noble is one such person. He’s spearheading a project called Bloodhound SSC that will visit uncharted territory on its way to a new land speed record on the far side of 1,000mph. The idea of a car capable of 1,000mph might sound ludicrous at first blush, but consider Noble's credentials. The British businessman is responsible for previous land speed records in 1983 and 1997, the first of which came with him behind the wheel.

A brief history of speed

Land speed record attempts are nearly as old as the car itself. After all, it couldn't have taken long for the first motorists to wonder how fast their new contraptions might go given sufficient room. By the early 20th century, record chasers were building special cars with nothing but straight line speed in mind. These higher speeds demanded ever more power thanks to immutable laws of physics; drag (air resistance) increases as the square of speed. In plain English, a car that needs 100hp to reach 100mph would need 400hp to reach 200mph, or 900hp to reach 300mph. More power meant bigger engines, often borrowed from the aircraft industry. Noble's Bloodhound SSC is a natural progression of this trend.

Land speed cars quickly became too fast for roads or even racetracks designed for more normal cars. High speed runs need as flat a course as possible, with nothing to hit and lots of room to build up to speed and then slow down again. Suitable beaches in Wales and Florida were host to a succession of records in the 1920s, which by then had arrived at a standard format—an average of two timed runs in opposite directions, within a certain time limit (originally 30 minutes, now an hour). Speeds soon outgrew Pendine and then Daytona Beach, so attempts headed inland. In 1937, Malcolm Campbell sped across the Bonneville Salt Flats at more than 300mph, making Utah the place to go if you wanted to chase records. His car, called Blue Bird, is recognizable as a car even today. The same goes for other prewar land speed record challengers with their rubber tires and internal combustion engines. By 1947, John Cobb was knocking on the door of 400mph, but it was becoming clear that future land speed records would need more power than a piston engine could offer.

The post-war aerospace industry was being built with jet engines and rocket motors. Both were lighter and more powerful than piston engines, as speeds quickly showed. In October 1947, less than a month after Cobb's 394mph record, Chuck Yeager and Bell's rocket-engined X-1 broke the sound barrier (700mph, or Mach 1.06) for the first time. It would take 50 years for a land speed car to travel faster than Yeager's historic flight, by which time rockets had propelled X-15 pilots across the skies of the southwestern United States at 4,500mph and brought Apollo astronauts back from the moon at almost 25,000mph. Jet-powered airplanes were also soon faster than the speed of sound. By the 1950s, small fighters like the F-104 Starfighter could exceed Mach 2 (1,200mph) for short bursts, but within a handful of years, Lockheed's A-12 could cruise at Mach 3, more than 2,000mph, for as long as it had fuel.

Both rockets and jets had land speed potential, although it would take some time before either was available outside of the military. Eventually, surplus jet engines started to find their way into civilian hands, into the hands of men looking to prove they, too, had the right stuff. Between 1963 and 1964, Craig Breedlove (407mph), Tom Green (413mph, and no, not that Tom Green), and Art Arfons (434mph) duked it out on the salt flats, each taking turns at being the fastest man on earth. The following year, Breedlove returned with authority—and the engine from an F-4 Phantom—and breached 600mph. In 1970 Gary Gabelich went faster still, using rocket power rather than a jet engine. Gabelich was the last to set a land speed record at Bonneville, with a two-way average of 622mph. His record stood for 13 years, eventually bettered by just 11mph. That's where Noble comes along with a car called Thrust 2.

Noble followed Thrust 2 in 1997 with Thrust SSC, this time with RAF pilot Andy Green in the driving seat.

Bloodhound's ancestors

Noble had been captivated by speed as a child after watching Cobb attempt to break a water speed record on Loch Ness in Scotland. Inspired by the achievements of fellow countrymen Campbell and Cobb, he wanted to reclaim the record for Britain. After building—and then crashing—one of the UK's first jet-powered cars (Thrust 1), he acquired a surplus engine from English Electric Lightning. The Lightning was Britain's late-1950s interceptor, designed to shoot down Soviet bombers over the North Sea. It was built around two powerful Rolls Royce Avon engines that gave it astonishing performance for the time. Just one of these engines was sufficient to convince John Ackroyd to accept Noble's job offer as Thrust 2's designer, and work began on the car in 1978, albeit in a shoestring fashion.

Thrust 2, now with a more powerful variant of the Avon engine, went to Bonneville at the end of September 1981. Until now, Noble had only driven the car on runways in the UK, never faster than 260mph. For two weeks the team built up speed at Bonneville before the rain arrived, flooding the lake and ending any record attempts for the year. Thrust 2 had peaked at 500mph, but Gabelich's record would stand for a while longer. Thrust 2 returned the following September to again find Bonneville's flats under several inches of water. Once it was clear that Bonneville was no good for anything other than hovercraft, the search was on for a new location.

Noble and Thrust 2 found themselves in the Black Rock desert in Nevada, now best known as the site of the Burning Man festival. Helpfully, the surface of the alkaline playa was much better suited to Thrust 2's solid metal wheels. (At Bonneville these had cut ruts into the salt, requiring a new track for each run.) 1982 wasn't to be Thrust 2's year either, averaging 590mph and teaching Noble and his team a lot before the weather came and stopped things. Finally in 1983 everything went according to plan, and on October 4, Thrust 2 reached a peak speed of 650mph, setting a new world land speed record of 633.5mph.

It's easy to see how the mindset required to successfully break a land speed record wouldn't be satisfied just doing it once; it seems everyone comes back for another bite at the cherry. Noble was no exception. He knew that Breedlove was planning on taking back the record and that the American had a pair of General Electric J-79 engines with which to do so. 700mph was the next headline speed, with the speed of sound not much further away. Eager not to lose the record, Noble planned to defend it with Thrust 2's successor, Thrust SSC (the initials stand for SuperSonic Car).

Thrust 2's success came despite the lack of any significant aerodynamic design or refinement. Going supersonic meant that aerodynamics couldn't be ignored any longer though. In 1992, Noble met the man who would design his new car, a retired aerodynamicist called Ron Ayers. Ayers would learn much on Thrust SSC—and another land speed car, 2006's diesel-powered JCB Dieselmax—that would inform his design for Bloodhound SSC. At first though, he was reluctant to get involved. "The first thing I told him was he'd kill himself," Ayers told Ars. Yet curiosity got the better of Ayers, and he began to see solutions for the various problems that at first made this look like an impossible challenge. A second chance meeting between Noble and Ayers followed, and before long Ayers was Thrust SSC's concept designer and aerodynamicist.

Now, Ayers had the problem of working out what shape a supersonic car ought to take. That came from computational fluid dynamics (CFD). No one had attempted to use computer modeling to design a land speed record car until then, but even now no wind tunnels capable of supersonic speeds also feature a rolling road, necessary to accurately account for the effect of having wheels at those speeds. The University of Swansea in Wales created a CFD simulation of a supersonic vehicle, but "the problem was, at that time neither I nor anyone else trusted [CFD]," Ayers explained. His skepticism vanished following tests with scale models fired down a rocket sled track belonging to the UK Defense establishment (located at Pendine Sands, the site of many 1920s land speed records). The CFD data matched that from the rocket sled track to within a few percent, something that astonished both Ayers and the other aerodynamicists with whom he shared his findings.

Thrust SSC would use a pair of Rolls Royce Spey engines, taken from a British F-4 Phantom, mounted quite far forward on either side of the car, with the driver's cockpit in-between. Together with a long, pointed nose and a T-shaped tail fin and stabilizer, Thrust SSC looked much more like a jet fighter with no wings than a car. Fittingly, the car got a driver to suit its looks. Land speed records aren't cheap, something Noble (and probably every other record chaser) knew from bitter experience. He managed to scrape together enough funding to make three record attempts with Thrust 2 even though his attention was split between fund-raising and learning how to operate and control the car. For the sequel he wisely decided to leave the driving to someone else, concentrating his efforts on leading the project and raising the money. Thirty people applied for the job, a mix of drag racers and fighter pilots. The successful candidate was one of the latter, RAF Wing Commander Andy Green. Green had plenty of supersonic experience in RAF Phantoms and tornadoes; he also had a daredevil streak, evident in his choice of hobbies.

By 1997 the car was ready for Black Rock Desert. So, too, were Breedlove and his Spirit of America, setting the stage for a transatlantic, transonic shoot-out. Spirit of America narrowly escaped disaster the previous year, turning sharply right at ~675mph and rolling onto its side in the process. 1997 was to be no kinder to the Americans. On October 15, a sonic boom announced to the world that Green (backed by Noble) was now the fastest man on earth. Thrust SSC set a two-way average of 763mph, or Mach 1.015, exactly 50 years and a day after the first Mach 1 flight.

Thrust SSC breaks the sound barrier.

Noble, Green, and Ayers set another land speed record in 2006, albeit with a much slower car. JCB Dieselmax set a new world record for a diesel-powered vehicle, reaching just over 350mph. Even though Bloodhound SSC will go much faster, Ayers told me they gathered a lot of useful knowledge then that is being applied to the current project.

Bloodhound SSC

A number of factors appear to be necessary for a land speed record attempt: a car with a sufficiently powerful engine, a suitable location, and someone motivated enough to raise the money to make it happen. A little bit of competition helps with the last of these. Breedlove, Green, and Arfons spurred each other on in the 1960s, and it was the threat of Breedlove going supersonic that sparked Thrust SSC. As you might expect, competition was also the original impetus behind Bloodhound SSC. Noble learned that Steve Fossett was planning a land speed record attempt. The ballooning adventurer bought Spirit of America from Breedlove in 2006, and he set his sights on 800mph. Noble needed a new car that incorporated the lessons learned from Thrusts 2 and SSC.

What makes the car go?

The key to any land speed record car is its engine, and Bloodhound SSC is no exception. Rather than depend on decades-old surplus, Noble and Green approached the UK government to see if they could help. "We thought we'd earned the right to do this properly with the right technology," Noble told the UK's Director magazine. The Ministry of Defense agreed on the condition that Bloodhound SSC be exciting enough a project to rekindle the interest in science and technology that Apollo or Concorde created in the 1960s and 1970s. In return for inspiring a new generation of engineers, Bloodhound SSC could have an EJ200 jet engine, a type more often found in the Eurofighter Typhoon.

Static test of Bloodhound SSC's EJ200 jet engine.

Thrust SSC needed the combined thrust of two Spey jet engines to break the sound barrier. To go 30 percent faster, Bloodhound SSC will need more power than a single EJ200 can provide—at full reheat just over 20,000lbf (90 kN), roughly as much as one of the two engines on its predecessor (albeit at half the weight). The Bloodhound team decided upon rocket power for the remaining thrust. We asked Ayers why they opted for this approach, and he explained that it had several advantages over a pair of jets. For one thing, it needs only one air intake, meaning a lower drag design than Thrust SSC's twin engines. To reach the kind of performance target Bloodhound SSC is aiming at with a pair of jets, it would require designing variable geometry air intakes. While this sort of engineering solution is used by fighter aircraft, it would add unnecessary cost, complexity, and weight to Bloodhound SSC. What's more, a rocket can provide much more thrust for its size and weight than a jet. Finally, using rocket power means being able to accelerate much more rapidly, which should help limit the length of track needed.

An early version of Bloodhound's hybrid rocket is about to be tested. The Cosworth F1 engine that powers the rocket's HTP pump can be seen underneath a dust sheet to the right of the tank.

The concept behind the cluster of four hybrid rocket engines that will sit underneath the EJ200 (providing the other 27,000lbf or 122kN) is particularly interesting. Generally, rockets are either liquid- or solid-fueled. The former trade temperamental propellants for the ability to throttle their power output (by controlling the mixture of that fuel and oxidizer). Solid-fuel rockets, as their name suggests, use a combined oxidizer and fuel in a solid matrix. This makes them much more stable, but less powerful and far less controllable. Once lit, a solid-fuel rocket is going to burn until it's done.

Conventional liquid-fuel rockets—like the Dynetics F-1 that reduces Review Editor Lee Hutchinson to a quivering jelly—require a lot of intricate plumbing to pump the right mixture of fuel and oxidizer into the combustion chamber. Those propellants can be a pain to work with. The Space Shuttle's liquid oxygen and hydrogen need cryogenic storage, which is a lot easier for NASA to do at Kennedy Space Center than it would be for the Bloodhound SSC team at the remote desert in South Africa they plan to use. And liquid oxygen and hydrogen are on the mild end. Hypergolic fuels and nitric acid-based oxidizers were beloved by Soviet rocket designer Valentin Glushko for the tantalizing amount of energy they could release without the need for expensive cooling. Of course, they're extremely toxic, highly corrosive, and some of them can set fire to wet sand. It's not really surprising that they've been at the heart of some of rocketry's mostcatastrophic failures.

Bloodhound SSC's cluster of rockets will use a liquid oxidizer—in this case, highly concentrated hydrogen peroxide (also known as high test peroxide or HTP)—and keep the ability to be throttled. A catalyst decomposes the HTP into steam and oxygen at 1,100 degrees Fahrenheit, a temperature hot enough to ignite the fuel, which is a synthetic rubber compound. The rocket will keep firing for as long as it's fed oxygen: keep pumping in HTP and it goes, stop pumping in HTP and it stops. The pump itself is adapted from the UK's aborted Blue Steel cruise missile, and it's designed to supply the rocket with more than 10 gallons of HTP every second. That in itself is no mean feat, and the car's auxiliary power supply will need at least 750bhp to drive the HTP pump. Until recently, Bloodhound SSC's plan called for a Cosworth Formula 1 engine as that auxiliary power supply, although now several alternate arrangements are being tested.

This is definitely cool and fascinating, but rocket on wheels isn't a car. IMHO, it shouldn't be called a car if the engines don't power the wheels. Powered wheels should be a requirement for "land speed" record.

It is cool to see things like this, but it is less of automotive engineering and more of aerospace engineering with smaller wings. While it is very interesting to see a car reach 1000 MPH, I'd personally like to see what they can do with a car that is still driven by it's wheels, whether it's an engine turning a driveshaft, or electric engines at the the wheels.

This is definitely cool and fascinating, but rocket on wheels isn't a car. IMHO, it shouldn't be called a car if the engines don't power the wheels. Powered wheels should be a requirement for "land speed" record.

I agree with you on the first part this isn't a "Car" however it is still a land speed record. They have to account for the wheels and ground and how that will effect the speed vs a plane which just has the air to worry about.

I appears that the current wheel driven record is 470.444 mph set in 2001 if I'm reading the chart correctly. There are other cars listed after that one but they have a lower speed so I think they are different categories

It is cool to see things like this, but it is less of automotive engineering and more of aerospace engineering with smaller wings. While it is very interesting to see a car reach 1000 MPH, I'd personally like to see what they can do with a car that is still driven by it's wheels, whether it's an engine turning a driveshaft, or electric engines at the the wheels.

1. this is about pushing the envelope of what can be done. That is the primary goal. Any such endeavor is pursued primarily with the intention of pushing further than has been done, i.e. the challenge of it. Kind of like climbing mountains and walking to the poles and such.

2. With the level of calculations and data sampling this actually ends up being quite valuable for CFD (computational fluid dynamics) simulations, as these efforts will add to the empirical data that can be used to validate and/or tweak CFD calculations for fast moving objects with complex aerodynamic interactions (fast spinning wheels, body moving slightly above a static surface, pressure wave interaction, very quickly changing speeds). So, interesting for the pure science contributions.

Wheel driven is a bigger limitation, this is the absolute record. Absolute records need to be done with no limitations on how you do it, only a limitation on the context. Land-speed means that the wheels must support the machine, otherwise no limitations.

This is then an exercise in wonderful madness that can give worthwhile contributions to humanity while pushing the boundary of what is possible and providing a spectacle.

This is of course interesting and cool, but I can't help feeling like "world land speed record" is becoming a sort of pointless record. These things aren't really land vehicles anymore, they're just aircraft or spacecraft that happen to be launched horizontally. Aussie Invader is a 62,000 lb thrust liquid-fueled rocket engine copied virtually without any change from any of 100 different small space launchers, and it would ALMOST reach orbit if you pointed it straight up. In what sense is this a 'car'? I have to believe that this crop of vehicles will be the last such, there's just nothing left to prove here except how completely insane you are to drive one of these things.

What I want to know is how do the tires withstand the centrifugal force while the "car" is traveling at 1000 mph? Heck, even at 600 mph...

edit: downvote? huh? i'm genuinely interested in this. i realize it does not have conventional tires with air or other gas, but there is some insanely high speed rotation, and i imagine they'd have to be extremely well balanced.

Although the article is very well-written, the persistent use of US customary units is very annoying to someone raised with SI units. Yes, it's an American site — which would explain why you'd use both. But not specifying proper, SI units for common measures essentially shows that you really don't care at all about your international readers. Thank you…

In plain English, a car that needs 100hp to reach 100mph would need 400hp to reach 200mph, or 900hp to reach 300mph.

This example is not correct. Drag (a force) does indeed, at least to first-order, increase with the square of the airspeed. But power is not proportional to force, it's proportional to force times velocity. Therefore the actual situation is even worse, as the power required to overcome drag actually increases with the cube of the velocity!

I'd be curious to see how fast a car could go with 2 F135-PW engines instead of a couple of EJ200s. P&W is already building/testing a 50Klb thrust-capable model. Granted, the F135 is 75% heavier than its European counterpart, but has potentially 250% of the power. 100,000lbs of force strapped to a car? Mach 2 might be within reach. Also, that's a ludicrous amount of power.

But what I want is someone, anyone to break both the "Rocket-powered aircraft" set in 1967 and "Manned air-breathing craft" set in 1976 to be broken 47 years and 38 years is far to long.

Not likely to happen. Anything moving as fast as the X-15 is just passing through the 4,500MPH mark on the way into space. The SR-71, likewise, has been replaced by a combination of space satellites and subsonic stealth drones. To beat either requires the resources of a government and those governments are likely to follow the US example of using lower-cost tech to solve similar problems.

There's an outside chance that there might be a Mach 3+ private jet, but there aren't enough billionaires to make that venture profitable for the foreseeable future.

What a total waste of money and talent. Human stupidity knows no limits, even with the smartest people.

Not in the least. This kind of engineering knowledge is how we better understand the world and design for it. As mentioned in the article, land speed record chasing is how we learned to trust computational fluid dynamics, which has helped us advance all kinds of vehicle design.

Just as with the work that NASA has done over the years. By itself, exploring space is so specialized a pursuit, that it's easy to see it as a waste for 99.999% of the world population, but the advanced in engineering and science that have come out of NASA programs not directly relating to space have had immeasurable impact on the rest of the world.

Clearing the stones and such off the course is essential not only to keep the airflow to the engine clear of debris. Imagine hitting a 1 cm stone with your aluminum wheel under 50,000 g force at 1000 mph . . . a bit worse than your average pothole.

This is definitely cool and fascinating, but rocket on wheels isn't a car. IMHO, it shouldn't be called a car if the engines don't power the wheels. Powered wheels should be a requirement for "land speed" record.

There are different categories for different classes, just as the article eluded to when it mentioned the diesel powered JCB Dieselmax.

But, of course, the most interest will be in the absolute highest speed possible with no restrictions on how you do it (bar staying on the ground).

This is definitely cool and fascinating, but rocket on wheels isn't a car. IMHO, it shouldn't be called a car if the engines don't power the wheels. Powered wheels should be a requirement for "land speed" record.

I agree with you on the first part this isn't a "Car" however it is still a land speed record. They have to account for the wheels and ground and how that will effect the speed vs a plane which just has the air to worry about.

I appears that the current wheel driven record is 470.444 mph set in 2001 if I'm reading the chart correctly. There are other cars listed after that one but they have a lower speed so I think they are different categories

I agree with you on the first part this isn't a "Car" however it is still a land speed record. They have to account for the wheels and ground and how that will effect the speed vs a plane which just has the air to worry about.

I think I have to agree with Zak. At this point the wheels are no longer really germane. Again, look at the Australian car, it is NOTHING more than a conventional rocket, the wheels hardly matter. Honestly, you could simply fly your rocket 1 meter over the ground and hang a wheel off the side. Its meaningless. Sure, its HARD to fly like that, but its still really flying. Its not as if any of these vehicles NEED wheels to roll on, its just a technicality.

What a total waste of money and talent. Human stupidity knows no limits, even with the smartest people.

Not in the least. This kind of engineering knowledge is how we better understand the world and design for it. As mentioned in the article, land speed record chasing is how we learned to trust computational fluid dynamics, which has helped us advance all kinds of vehicle design.

Just as with the work that NASA has done over the years. By itself, exploring space is so specialized a pursuit, that it's easy to see it as a waste for 99.999% of the world population, but the advanced in engineering and science that have come out of NASA programs not directly relating to space have had immeasurable impact on the rest of the world.

Furthermore, although only very lightly touched on here, this whole project has been pulled very heavily into British schools to connect kids with a very sophisticated and glamorous STEM project. The BBC has a lot of examples of the educational outreach done with Bloodhound.

I agree with you on the first part this isn't a "Car" however it is still a land speed record. They have to account for the wheels and ground and how that will effect the speed vs a plane which just has the air to worry about.

I think I have to agree with Zak. At this point the wheels are no longer really germane. Again, look at the Australian car, it is NOTHING more than a conventional rocket, the wheels hardly matter. Honestly, you could simply fly your rocket 1 meter over the ground and hang a wheel off the side. Its meaningless. Sure, its HARD to fly like that, but its still really flying. Its not as if any of these vehicles NEED wheels to roll on, its just a technicality.

Absolutely not. If you cannot control precisely the interactions with both the surface and the boundary layers, you will be involved in a possibly world record explosion long before you are supersonic. When you have actually flown a rocket one meter off the ground, hanging a small wheel to the ground at 1000 mph, let me know. Otherwise I am sending flowers to your next of kin.

What a total waste of money and talent. Human stupidity knows no limits, even with the smartest people.

Not in the least. This kind of engineering knowledge is how we better understand the world and design for it. As mentioned in the article, land speed record chasing is how we learned to trust computational fluid dynamics, which has helped us advance all kinds of vehicle design.

Just as with the work that NASA has done over the years. By itself, exploring space is so specialized a pursuit, that it's easy to see it as a waste for 99.999% of the world population, but the advanced in engineering and science that have come out of NASA programs not directly relating to space have had immeasurable impact on the rest of the world.

Furthermore, although only very lightly touched on here, this whole project has been pulled very heavily into British schools to connect kids with a very sophisticated and glamorous STEM project. The BBC has a lot of examples of the educational outreach done with Bloodhound.

Yep, this is a very big aspect of the project, but one I chose not to focus on too much for this audience. Their outreach to schools in the UK, South Africa, and across the world is laudable.

I agree with you on the first part this isn't a "Car" however it is still a land speed record. They have to account for the wheels and ground and how that will effect the speed vs a plane which just has the air to worry about.

I think I have to agree with Zak. At this point the wheels are no longer really germane. Again, look at the Australian car, it is NOTHING more than a conventional rocket, the wheels hardly matter. Honestly, you could simply fly your rocket 1 meter over the ground and hang a wheel off the side. Its meaningless. Sure, its HARD to fly like that, but its still really flying. Its not as if any of these vehicles NEED wheels to roll on, its just a technicality.

Absolutely not. If you cannot control precisely the interactions with both the surface and the boundary layers, you will be involved in a possibly world record explosion long before you are supersonic. When you have actually flown a rocket one meter off the ground, hanging a small wheel to the ground at 1000 mph, let me know. Otherwise I am sending flowers to your next of kin.

Its not a question of whether its HARD or not, its a question of whether it has anything whatsoever to do with the concept of being a 'land vehicle'. Its simply not meaningfully a different category of thing. Its just "stupid tricks we are doing with a rocket" at this point. Thus calling these things "world land speed records" is becoming silly. The truth is that technology has simply outstripped and made pretty much meaningless this category of competition and records. So, like Zak, I find the more limited "wheel driven speed record" category to be a lot more meaningful, at least we're clearly still dealing with land vehicles (though frankly most of them probably have enough power to fly if you put some wings on them...).

I agree with you on the first part this isn't a "Car" however it is still a land speed record. They have to account for the wheels and ground and how that will effect the speed vs a plane which just has the air to worry about.

I think I have to agree with Zak. At this point the wheels are no longer really germane. Again, look at the Australian car, it is NOTHING more than a conventional rocket, the wheels hardly matter. Honestly, you could simply fly your rocket 1 meter over the ground and hang a wheel off the side. Its meaningless. Sure, its HARD to fly like that, but its still really flying. Its not as if any of these vehicles NEED wheels to roll on, its just a technicality.

Absolutely not. If you cannot control precisely the interactions with both the surface and the boundary layers, you will be involved in a possibly world record explosion long before you are supersonic. When you have actually flown a rocket one meter off the ground, hanging a small wheel to the ground at 1000 mph, let me know. Otherwise I am sending flowers to your next of kin.

Its not a question of whether its HARD or not, its a question of whether it has anything whatsoever to do with the concept of being a 'land vehicle'. Its simply not meaningfully a different category of thing. Its just "stupid tricks we are doing with a rocket" at this point. Thus calling these things "world land speed records" is becoming silly. The truth is that technology has simply outstripped and made pretty much meaningless this category of competition and records. So, like Zak, I find the more limited "wheel driven speed record" category to be a lot more meaningful, at least we're clearly still dealing with land vehicles (though frankly most of them probably have enough power to fly if you put some wings on them...).

This might have been germane in the 1960s when people started using rocket and jet thrust to set new speed records in wheeled vehicles; 50 years down the road and several hundred miles an hour faster that horse has well and truly bolted. It's an official FIM record, and it's an answer to the question "just how fast can we go in a vehicle that sits on four wheels?"

This might have been germane in the 1960s when people started using rocket and jet thrust to set new speed records in wheeled vehicles; 50 years down the road and several hundred miles an hour faster that horse has well and truly bolted. It's an official FIM record, and it's an answer to the question "just how fast can we go in a vehicle that sits on four wheels?"

Sits on 4 wheels or "just happens to touch (some) wheels to the ground?" As I say, any of these vehicles is QUITE capable of flying and has enough power to perform a space launch. Calling them "land vehicles" seems sort of silly...

If you strapped wings to any car capable of 200 mph (and there are quite a lot now) then those could take off too, but they wouldn't fly and they're not designed to. Just like Bloodhound and Thrust and the rest of them are not designed to fly, even if they borrow from aerospace.

I explained in relative detail why Bloodhound is a car - it has the same suspension and steering as a car, it brakes like a car (at low speed), it steers with a steering wheel and has accelerator and brake pedals.

I was under the impression that solid fuel rockets were more powerful than liquid fuel rockets, and that the primary tradeoff is power for variable throttle.

Yes and no, you need to look at power to what?, Power to weight ratio?, power per density . How fast do it combust (you don’t want to fast because it just explode (can’t contain pressure without massive weight )).Liquid fuels, Hydrogen and oxygen is the most powerful in power to weight ratio (if i remember correctly), however it requires heavy cooling , and it energy density is low. saturn 5 that used kerosene/LO2 needed to be 110.6 m high, 10.1 meter wide (363 , 33 feet).liquid fuels also as the advantages that it can be turned off mid burn and can be variable throttled .

Solid fuel has much higher energy density , by a lot. and the fuel can be more stable and no cooling system required . however it is heavier then liquid and remember the more weight that needs to be lifted the more power it needs in the first place. so to go to the moon on solid rockets would be impractical .edit: Clarified that the saturn 5 was an example of rocket using liquid fuels for power. an that its about energy density versus energy per weight (2 different and important things)

This is definitely cool and fascinating, but rocket on wheels isn't a car. IMHO, it shouldn't be called a car if the engines don't power the wheels. Powered wheels should be a requirement for "land speed" record.

1. this is about pushing the envelope of what can be done. That is the primary goal. Any such endeavor is pursued primarily with the intention of pushing further than has been done, i.e. the challenge of it. Kind of like climbing mountains and walking to the poles and such.

2. With the level of calculations and data sampling this actually ends up being quite valuable for CFD (computational fluid dynamics) simulations, as these efforts will add to the empirical data that can be used to validate and/or tweak CFD calculations for fast moving objects with complex aerodynamic interactions (fast spinning wheels, body moving slightly above a static surface, pressure wave interaction, very quickly changing speeds). So, interesting for the pure science contributions.

Wheel driven is a bigger limitation, this is the absolute record. Absolute records need to be done with no limitations on how you do it, only a limitation on the context. Land-speed means that the wheels must support the machine, otherwise no limitations.

This is then an exercise in wonderful madness that can give worthwhile contributions to humanity while pushing the boundary of what is possible and providing a spectacle.

It's a win-win-win-win scenario!

People just don't realize - and it's often maddening - that many of the things they use everyday and take for granted were originally born out of "crazy" science/engineering experiment or at least indirectly made possible by such. Better car bodies, stronger and lighter materials, better suspension, brakes, better lubricants, control system, safety improvements, etc.

It is cool to see things like this, but it is less of automotive engineering and more of aerospace engineering with smaller wings. While it is very interesting to see a car reach 1000 MPH, I'd personally like to see what they can do with a car that is still driven by it's wheels, whether it's an engine turning a driveshaft, or electric engines at the the wheels.

Yeah, exactly!

We were typing essentially the same comment, you clicked submit a minute or two before me.

Clearing the stones and such off the course is essential not only to keep the airflow to the engine clear of debris. Imagine hitting a 1 cm stone with your aluminum wheel under 50,000 g force at 1000 mph . . . a bit worse than your average pothole.